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My engine has piston slap after i changed pistons to arias forged pistons. I can hear slap when engine is cold and when is hot . What i have to do for repair slap ??? should i bore/hone the cylinders to bigger diameter or opisit i should get oversized pistons ??? sorry for my english

Originally posted by 1 Lucky Texan Aren't some (all?) Sube pistons marked for orientation due to wrist pin being slightly off center? Maybe that's the older engines but what would happen if he installed them 'upside down'?

Carl
1 Lucky Texan

i have wrx 2002
EJ 20 engine
stock piston have mark for right orientation
arias forged piston do not have mark for right orientation because pin bore is precisely in middle of skirt
arias skirt is longer then stock

At the very least I think you should get a refund on the new pistons. The reason the stocks have a slightly offset wrist pin is to reduce piston slap! I do agree a longer/different skirt design might do the same. However this all points to the same conclusion. Your new pistons are poorly designed for your application.

Originally posted by 1 Lucky Texan At the very least I think you should get a refund on the new pistons. The reason the stocks have a slightly offset wrist pin is to reduce piston slap! I do agree a longer/different skirt design might do the same. However this all points to the same conclusion. Your new pistons are poorly designed for your application.

Well, perhaps they are not poorly designed. Still, they could be undersized or have some other defect.

How long was your engine open during the work? Maybe there is some other source of the noise? TB tensioners can be noisy, lifters,etc. If you engine was inoperable for a while the oil could have gotten gummy or something.